1. Field of the Invention
The invention relates to a bogie frame for a rail vehicle, which incorporates two longitudinal members in the form of open or closed hollow profiles, and at least one transverse member, where the hollow profile of the longitudinal member is formed by wall elements having a particular thickness.
The invention can be applied both to bogie frames with the bogie bearings mounted internally, whereby in the assembled state the wheels of the rail vehicle are arranged outside the longitudinal members, and can also be applied to bogies with external bearings.
2. Description of the Related Art
In a bogie, the transmission of force between the various functional units, such as the drive or brake, is handled by the bogie frame. Especially in the case of bogies for high-speed trains, high longitudinal and diagonal rigidity of the bogie frame is an operational requirement for the wheel sets. Due to the high loadings arising in operation, and the required operational security, the bogie frame is manufactured at high material and production costs. Apart from the high costs in technical respects, this results in the bogie frame having a high weight.
In order to accommodate the high loadings on the bogie frame, to manufacture the bogie frame use is made of open or closed hollow profiles that are produced from plates that are welded together. In operation, the welded seams are subject to basically high loadings.
In the case of closed hollow profiles, the production of an opposing welded seam on the side of the welded seam root is no longer possible, due to the lack of accessibility, so that the welded seam cannot be subjected to the same forces as when made with an opposing weld. Here, the plate thicknesses must be increased to be able then to make the welded seam thicker and thus also stronger. Alternatively, the longitudinal member can be made with a cover, which makes it possible to weld the welded seams in the inside. Disadvantages of this method are a significantly increased production expenditure due to the longer welding time, an increased manipulation expenditure, and the covering parts that are additionally required. In summary, the weight of the bogie frame and the production costs are further increased.